<ul>
  <li>You can set a custom (fixed) layout width for this page template.</li>
  <li>The value will be saved when you click somewhere outside the input field.</li>
  <li>If you leave this empty, the global layout width will be used for this page template.</li>
  <li>The global layout width can be set at "Global Settings" -> "Layout Widths".</li>
</ul>